Measurement systems such as x-ray diffraction devices, neutron diffraction devices or similar diffraction devices that use other radiation sources, rely on a diffraction pattern from the radiation scattered by a sample to make a desired measurement. An x-ray diffraction system operating in this manner is depicted in schematic form in FIG. 1. As shown, the system is arranged for transmission mode diffraction. An x-ray radiation source 10 directs a beam of x-rays 12 onto a specimen 14 to be examined. The x-rays are scattered from the specimen in a pattern indicative of its atomic structure. This scattered energy may thereafter be detected by a two-dimensional (2D) detector 18, which detects the transmission variation of the scattered signal in the plane perpendicular to the direction of the original beam.
As in most transmission mode diffraction systems using 2D detectors, this system uses a beamstop 20 to block the direct x-ray beam that passes through the sample from reaching the detector. This prevents the detection of the diffracted energy from being disturbed by interaction of the high-energy transmitted x-ray beam with the detector. However, in certain circumstances, it is desirable to measure the intensity of the transmitted beam to allow normalization of the diffraction data against the sample thickness (or density) variation. The conventional manner of doing so is shown in FIG. 1. A glassy-carbon (GC) filter 16, which has high-angle scattering that is featureless, is inserted in the path of the transmitted x-ray beam, and the resulting two-dimensional pattern is detected. From this, the desired information regarding the intensity of the transmitted beam may be determined.
While the use of a GC filter has proven a satisfactory way of detecting the transmitted beam intensity, it requires the insertion and removal of the filter. Furthermore, a separate detection step must be performed for each of the transmitted beam and the actual diffracted x-ray energy. This creates delays and additional steps in the ultimate x-ray diffraction measurement process.